This particular invention relates generally to film processing and, more particularly, it concerns a method and photographic film cassette having an improved system for releasing processing fluid from a processing fluid applicator.
Multipurpose film cassettes for use in the motion picture art have been developed in which a strip of photographic film is selectively and sequentially operated to be exposed, processed and projected while at all times remaining in the cassette. Film cassettes of this type are disclosed in several U.S. Patents assigned in common with the present invention.
Typically, such cassettes contain a supply of light-sensitive photographic film. For selectively exposing the film, the cassette is placed in a camera particularly adapted to receive and operate the same. Processing or developing of the exposed film to provide the conventional series of positive transparent image frames is achieved by placing the cassette in a player or processing and viewing apparatus. This player apparatus activates a cassette contained fluid processor for effecting deposition of processing fluid for developing the latent images on the exposed emulsion surface while the latter is advancing therepast. Following processing as indicated above, the player apparatus is operated as a projector. During the projecting mode, the film is incrementally advanced, frame-by-frame, past a light source. In this manner, the transparent images of the scenes to which the film were exposed are capable of being successively viewed while being projected onto a screen.
The advance in the motion picture art represented by such a system is apparent and needs no elaboration herein. However, for satisfactory cassette performance it is vital that desposition of the processing fluid be reliably controlled. Otherwise, incomplete and non-uniform coatings may arise thereby possibly adversely affecting achievement of a uniform diffusion transfer on the film strip as well as possible contamination of cassette components. It follows, therefore, that the achievement of controlled fluid release onto the film strip during processing has been a major focal point of attention in overall system development.
The current state of the art with respect to achieving the appropriate release of the processing fluid on such cassette contained film strip is represented by the disclosures of U.S. Pat. No. 3,895,862 issued July 22, 1975, to Joseph A. Stella, Edward F. Burke, Jr. and Paul B. Mason; and U.S. Pat. No. 3,951,530 issued Apr. 20, 1976, to Frank M. Czumak, Paul B. Mason and Joseph A. Stella; all of which patents are commonly assigned with the present invention.
In cassettes of the foregoing category, the processing fluid is stored in a closed reservoir or pod positioned within the film cassette. Use is made of a removable tear-tab closure for ensuring releasable retention of the stored fluid. In this regard, the tear-tab is releasably bonded to the reservoir to seal completely the reservoir opening. For effecting opening of the reservoir opening, the tear-tab is provided with a folded back portion trained over a guide roller and connected to and movable with a pull strip. Opening commences when a latching tongue of the pull strip engages and moves with an aperture in the leader end of the film during rewinding of the exposed film strip back to the supply spool. Continued rewinding will produce a pulling displacement on the pull strip. This displacement is translated into corresponding displacement of the tear-tab. By virtue of the configuration and connection of the tear-tab, it will be peeled from the reservoir opening to thereby allow flow of the processing fluid through a processor nozzle opening onto the film strip.
In systems of this general type, separation and storage of the tear-tab from the pull strip is necessary for avoiding having the tear-tab, which is wet with processing fluid, from contaminating dry portions of the film strip as well as other cassette components. Towards this particular end, the art teaches that the tear-tab closure is separated by a knife-like formation. This formation is at the exit of a channel formed by internal cassette walls which walls also form a storage chamber for the separated tear-tab. While the foregoing approach is successful in operation, it nevertheless requires a relatively large number of components and is subject to potential problems associated with the separation and subsequent storage of the wet tear-tab. More particularly, the tab may accidentally leave a storage chamber after separation, stick in the internal passages and if required to be displaced by pushing would have a tendency to buckle due to its thin and wet characteristics. Because of such potential, there is need for improvement in preventing the wet tear-tab from adversely affecting the film strip and the cassette components as well as an approach requiring fewer components for purposes of reducing costs.
Moreover, the problems of achieving a simple and controlled release of the processing fluid in a manner which avoids processing fluid contamination are further compounded by the requirement that each once used cassette carry its own processor. Moreover, the cassette and its components, including the processor, must be capable of mass production manufacturing techniques and the tolerance levels incident to such techniques for the system to be acceptable in a competitive commercial market. Accordingly, the structural organization of the means by which the processing fluid is released for deposition onto the film is critical to the overall system in which the cassette is used.